Effect of Afforestation with Broadleaf Species on Carbon Sequestration in Soil of Chitgar Forest Park of Tehran

In recent years, the increment of atmospheric CO2, which is one of the main green house gases, has caused the global warming and climate changes. It has unfavorable effects on environment and humankind life on earth. Whereas forests and afforestation regions in degraded and uncultivated lands have significant influence on the carbon sequestration. This research was done in Robinia Pseudoacacia and Fraxinus rotundifolia stands and the surrounding degraded range as blank and the sequestrated carbon was measured. Besides, the relation between some physical and chemical properties of soil and soil organic carbon (SOC) was investigated. The results showed that total sequestrated carbon in unit area of Robinia Pseudoacacia and Fraxinus rotundifolia stands were, respectively, 78.19 and 48 ton/ha, while it was 10.8 ton/ha in degraded rangeland. The amount of SOC in the first layer of soil was more than the second layer in the two mentioned stands, but it was the opposite in the blank. Also, the results of step-wise regression analysis indicated that pH, sand, and nitrogen content were, respectively, the most important factors affecting soil organic carbon content. The results of correlation analyses showed that there was a positive significant relation between SOC with gravel and sand percentages, but it had a negative significant relation with pH, silt, and clay percentages. The economical value of this amount of carbon sequestration with the two mentioned stands was calculated at about 10.4 and 2.5 millions dollars, respectively, over the total area of Chitgar Park.